Turkish prosecutors launched an investigation Saturday of two United States prosecutors involved in putting a Turkish-Iranian gold trader Reza Zarrab on trial for allegedly violating U.S. sanctions against Iran, according to Turkish Anadolu news agency.

The İstanbul prosecutor's office said it was investigating Preet Bharara, the former U.S. attorney for the Southern District of New York, and Bharara's successor, Acting U.S. Attorney Joon H. Kim. İstanbul prosecutors have opened an investigation against both Bharara and Kim on the grounds that their actions "are clearly against the international and domestic law". It said that the evidence being used in the case against the "Turkish citizens" is "stolen, of fraudulent nature and unidentifiable in origin."

Turkish President Recep Tayyip Erdoğan and his AKP government call the case political motivated. They have accused Bharara of links to U.S.-based Islamic preacher Fethullah Gülen, one of the masterminds of last year's failed coup attempt.

The move came after NBC in the United States reported Thursday that pro-Erdoğan gold trader Zarrab was now cooperating with prosecutors, raising the prospect that he may be seeking a plea bargain deal and give evidence for the prosecution. Neither Zarrab nor his lawyer attended a court hearing in Manhattan on Thursday to discuss the case ahead of the trial.

Nine people have been criminally charged, but only Zarrab and a banker from Turkey's Halkbank, Mehmet Hakan Atilla, are in U.S. custody. They are to go on trial on November 27, a case some commentators see as potentially damaging for Ankara.

Former Turkish Economy Minister Zafer Cağlayan is also among the nine defendants indicted in the case.

Zarrab was arrested by U.S. authorities in Miami in March 2016 on charges of helping Iran process millions of dollars of transactions when it was under U.S. sanctions for its nuclear program. The case threatens to reopen a case that reached right into Erdoğan’s inner circle. It will also deepen existing tensions between Turkey and the United States. Zarrab was detained and charged in İstanbul in 2013 in a huge corruption case. All charges against Zarrab and those linked to Erdoğan's government were dropped.

The U.S. case was built on work initially performed by pro-Fethullah Gülen Turkish investigators who targeted Erdoğan over gold trader Zarrab in 2013 in a sweeping corruption scandal that allegedly led to Turkish government officials. The evidence of the case, leaked tapes, elicited by the network of the Gülen, which had been organised in the police, judiciary, military and the other states institutions. Gülen had been a close ally of the then-Prime Minister Recep Tayyip Erdoğan, helping him to redesign and install his Islamic-rooted Justice and Development Party (AKP) in power in 2002. But his alliance with the AKP has faltered in recent years, especially in 2013 when police detained dozens of Erdoğan's key business and political allies over bribery allegations.

Erdoğan has repeatedly accused the network of Gülen, which is also an Islamic cult, of engineering the corruption scandal as well as a string of damaging leaks in the media.

"We will enter their caves and... they will pay the price. There won't be a state within a state," Erdoğan had said.

In the PBS interview, Erdoğan said that Gülen and he had had "good relations". "The real problem began after 2011," he said. That was when Erdoğan's government accused the network of Gülen leaking information from secret talks between the Turkish spy agency and armed Kurdish PKK group.

On 15 July 2016, the network of Gülen attempted to topple down Erdoğan by a military coup but it failed. There were more than a few traces of Pentagon and CIA behind the coup attempt. Fethullah Gülen emerged in the arena of politics within the ranks of the "Organization of the Struggle against Communism". This organisation was founded in 1960's by the CIA. Erdoğan, the primary target of the coup, and the coup plotters share the same ideological and political background.

Tensions emerged due to the AKP government's exaggerating Turkey's regional possibilities and failing to meet the expectations of the United States and some other imperialist countries, have reached to the point where it would disrupt relations between Erdoğan and the western countries, and eventually the United States, in order to create a more useful power for itself, stood behind the coup attempt.